Systems containing multiple infusion pumping units, sensing units such as blood pressure monitors and pulse oximeters, and other patient-care units are known in the medical field. For example, Kerns et al (U.S. Pat. No. 4,756,706; "Kerns") discloses a centrally managed pump system in which pump and monitoring modules are selectively attached to a central management unit. The central management unit controls the internal setup and programming of the attached modules, and receives and displays information from them. Each module is capable of being detached from the central management unit except for the first module, which is permanently attached. Once attached and programmed, a module which is subsequently detached is still capable of operating independently of the management unit.
Kerns provides for attachment of the modules in a vertical stacking sequence in a manner similar to that shown in FIG. 1. Attachment of an additional unit to the modular patient care system involves a multiple step process. These steps include (1) sliding a support plate 62 of the additional unit into the channel 64 of a previous unit, and (2) turning a knob 120, causing male connectors 122 and 124 of the additional unit to pop up and mate with corresponding female portions in the previous unit (Kerns FIG. 3 and col. 4 lines 7-16). Thus, achieving mechanical and electrical connectivity in Kerns clearly involves a multi-step, two-handed operation.
Further, Kerns provides for distinct, direct electrical connectivity from each stack module to the central management unit. Each module is provided with a separate AC power signal from the central management unit AC+ and AC- leads. Each module also contains its own power supply for autonomous operation when disconnected from the central management unit (Kerns FIG. 6).
Kerns has several disadvantages. First, for electrical and mechanical connectivity of an added unit to the central management unit, a multi-step, two-handed operation is needed, which may be cumbersome and time consuming in the medical environment. Second, because each module requires its own set of electrical paths to the central unit, the total number of modules which may be stacked is only one greater than the number of pass-through cables in each module. For example, for the pass-through structure shown in Kerns FIG. 4f, only four modules total may be accommodated by a system which uses these modules. Third, there is added weight, cost, and complexity due to the multiple cabling structure. For example, each signal of each cable must have its own contact pin in among the pins 122 of the contact structure of Kerns FIG. 3. Finally, the presence of a power supply in each functional module adds weight and cost.
Rubalcaba (U.S. Pat. No. 4,898,578) also discloses a drug infusion system which includes a plurality of infusion pump modules selectively attached to a central management unit so as to provide for centralized control. In particular, the central management unit obtains infusion parameters from the user and then performs calculations with the parameters to establish the desired infusion rate. Once this rate is determined, the central management unit may control the infusion accordingly. Rubalcaba, however, provides no solution for the problems related to electrical and mechanical connectivity of units described above with respect to Kerns.
Accordingly, it is an object of the present invention to provide a modular patient care system wherein modules are detachably connected to each other in a convenient, flexible, interchangeable, and secure manner.
It is another object of the present invention to provide a modular patient care system wherein each functional unit is powered by the central management unit using a common power bus scheme to avoid a multiplicity of power lines.
It is a further object to provide a flexible, bilateral power scheme wherein any functional unit may be placed anywhere in a linear array of units and be adequately powered. It is a further object of the present invention to make this powering scheme safe by avoiding active power supply voltages at exposed ends of the power bus.